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PHENIX Charm Results in Au-Au, d-Au and p-p Collisions.

PHENIX Charm Results in Au-Au, d-Au and p-p Collisions. Wei Xie (Riken-BNL Research Center) for PHENIX Collaboration. RHIC/AGS users meeting in 2004. P ioneering H igh E nergy N uclear I nteraction e X periment (460 participant from 57 institutions of 12 countries)

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PHENIX Charm Results in Au-Au, d-Au and p-p Collisions.

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  1. PHENIX Charm Results in Au-Au, d-Au and p-p Collisions. Wei Xie (Riken-BNL Research Center) for PHENIX Collaboration RHIC/AGS users meeting in 2004

  2. Pioneering High Energy Nuclear Interaction eXperiment (460 participant from 57 institutions of 12 countries) • Maximal Set of Observables • Photons, Electrons, Muons, ID-hadrons • Highly Selective Triggering • High Rate Capability. • Rare Processes.

  3. l Motivation for Charm measurements K+ e-/- e-/- e+/+ J/y K- • Sensitive to initial gluon density and gluon distribution e+/+ l D0 • Sensitive to initial gluon density and gluon distribution • Energy loss when propagating through dense medium • Suppression or enhancement of charmonium in the medium is a critical signal for QGP. • Different scaling properties in central and forward region indicate shadowing, which can be due to CGC.

  4. PHENIX Ability to Study Charm -- electron and muon measurement • high resolution tracking and momentum measurement from Drift chamber. Good electron identification from Ring Imaging Cherenkov detector (RICH) and Electromagnetic Calorimeter (EMCal). Good momentum resolution and muon identification from mID and mTrk. High rate capability • Open charm. • flow of charm. • J/y, y’ • Upsilon

  5. cocktail e+ γ e- Converter -einvariant mass Au Au Measure Open Charm via electrons in central arms • Subtraction of“photonic” sources. • conversion of photons from hadron decays in material • Dalitz decays of light mesons (p0, h, w, h, f) • Converter method • Comparison of e+/- spectra with and without converter allows separation of photonic and non-photonic sources of single electrons. • measurement via -e coincidences • Yield of -e in vicinity of  mass with mixed event subtraction Details see poster by Xinhua Li: “Charm Production in 200GeV p-p Collisions from PHENIX Experiment at RHIC”

  6. What has been Measured so far in Central Arms • Non-Photonic Single Electron Spectra: • with 1mb-1s = 130 GeV Au-Au collisions in RUN1 • with 100nb-1s = 200 GeV p-p collisions in RUN2 • with 2.74nb-1s = 200 GeV d-Au collisions in RUN3 • with 24mb-1s = 200 GeV Au-Au collisions in RUN2

  7. PHENIX: PRL 88(2002)192303 NLO pQCD (M. Mangano et al., NPB405(1993)507) PYTHIA ISR +332 -281 cc=709b±85(stat) (sys) PHENIX Non-Photonic Single Electron Spectra pp s = 200 GeV PHENIX PRELIMINARY 130GeV PHENIX data is consistent with the prediction of NLO pQCD calculation and PYTHIA prediction.

  8. PHENIX PRELIMINARY PHENIX PRELIMINARY PHENIX PRELIMINARY 1/TABEdN/dp3 [mb GeV-2] 1/TABEdN/dp3 [mb GeV-2] 1/TAB 1/TAB 1/TABEdN/dp3 [mb GeV-2] 1/TABEdN/dp3 [mb GeV-2] 1/TABEdN/dp3 [mb GeV-2] 1/TAB 1/TAB PHENIX Non-Photonic Single Electron Spectra d-Au s = 200 GeV • Scale with number of collision in d-Au collision • no indication of shadowing effect at mid-rapidity.

  9. 1/TABEdN/dp3 [mb GeV-2] 1/TABEdN/dp3 [mb GeV-2] 0.906 <  < 1.042 1/TAA 1/TABEdN/dp3 [mb GeV-2] 1/TAA 1/TAA Yellow band represents the set of alpha values consistent with the data at 90% Confidence Level dN/dy = A (Ncoll) 1/TABEdN/dp3 [mb GeV-2] 1/TABEdN/dp3 [mb GeV-2] 1/TABEdN/dp3 [mb GeV-2] 1/TABEdN/dp3 [mb GeV-2] 1/TAA 1/TAA 1/TAA PHENIX Non-Photonic Single Electron Spectra Au-Au s = 200 GeV • data seems to scale with Ncoll in all the centrality bins

  10. 130 GeV Au+Au (0-10%) D from PYTHIA D from Hydro B from PYTHIA B from Hydro e from PYTHIA e from Hydro (S. Batsouli, S.Kelly, M.Gyulassy, J.Nagle) Phys.Lett. B557 (2003) 26-32 Charm Energy Loss in the Medium Scaling with Ncoll seems to indicate little energy loss. “dead-cone” effect (D.E. Kharzeev et al.,Physics Letter B519(2001)199-206) Charm might thermalize and flow with others. The calculated electron spectrum is also consistent with the current electron data.

  11. PHENIX PRELIMINARY Charm v2: another way to look at the Energy loss Charm quark v2 is expected to be zero if there is no energy loss PHENIX RUN2 data can not distinguish different scenario due to small statistics. PHENIX accumulated a factor of 80 more statistics with better quality and less conversion background (0.3% instead of 1.4% )in RUN4. Expected to have much more clear answer.

  12. In Central region: Qs<m(cc) open charm production is expected to scale with Ncoll In forward region: Qs>m(cc). Open charm production is expected to scale with Npart(AA) and (pA) in forward rapidity region. Open Charm Measurement in forward region and CGC D.E. Kharzeev, K. Tuchin, hep-ph0310358 Ongoing PHENIX open charm analysis on muon channel is expected to give the answer

  13. J/y Measurement at RHIC Different prediction on J/y behavior when QGP is formed: Color screening will lead to suppression of charmonium production in heavy ion collisions(T. Matsui, H. Satz, Phys. Lett. B178(1986)416). • But after taken the recombination into account, much less suppression or event enhancement is predicted: • A. Andronic, P.B. Munzinger et al., nucl-th/0303036 • L. Grandchamp, R. Rapp, hep-ph/0103124 • R.L. Thews et al., Phys. Rev. c63(2001)054905 First Need to disentangle normal nuclear effect.

  14. gluons in Pb / gluons in p Anti Shadowing Shadowing X Eskola, et al., Nucl. Phys. A696 (2001) 729-746. What is the Cold Nuclear Effect There’s also suppression or enhancement due to normal nuclear effect: • Gluon(anti)shadowing • Nuclear absorption. • Initial state energy loss. • Cronin effect Nuclear effect expected to be understood through p-p and p(d)-A collisions. PHENIX has measured J/y production in p-p, d-Au and AuAu Collisions

  15. What has been Measured so far • J/y production • at s = 200 GeV p-p collisions in RUN2 and RUN3 • at s = 200 GeV d-Au collisions at RUN3 • at s = 200 GeV Au-Au collisions in RUN2

  16. J/y rapidity Distribution In RUN3, we accumulated ~300nb-1 p-p and ~3nb-1 d-Au collisions.

  17. Gluon Shadowing and Nuclear Absorption Vogt, PRL 91:142301,2003 Kopeliovich, NP A696:669,2001 RdA RdA Low x2 ~ 0.003 (shadowing region) High x2 ~ 0.09 Low x2 ~ 0.003 Data favor weak shadowing and weak nuclear absorption effect. Steep rise of RdA with increasing Ncoll at large X2. Need more data to distinguish different models.

  18. X2 (in gold) Initial State Energy Loss • Energy loss expected to be weaker with increasing s (B. Kopeliovich et al., Nuclear Physics A696(2001)669-714) The speculation are: • Energy loss dominant at SPS • Energy loss is less at E866 energy • Energy loss negligible at RHIC

  19. Cronin Effect: pT broadening Parton initial state multiple scattering leads to broadening of J/y pT distribution x2~ 0.003 x2~ 0.01 Broadening comparable to lower energy (s = 39 GeV in E866) x2~ 0.1

  20. A modest baseline for the study of J/ψ in AuAu collisions has been obtained from our p-p and d-Au measurement. • Although the errors in the dAu data are substantial, they might be small enough to separate cold nuclear matter from any further medium effect occuring in the hot-dense medium created in Au-Au collision

  21. J/y Measurement in Au-Au Collisions at snn=200GeV J/y signal reconstructed: 13 counts Dy = 1.0 Coalescence model Thews et al., hep-ph/0009090 Stat. Model Andronic et al. nucl-th/0303036 Dy = 4.0 Absorption model Grandchamp, R. Rapp, Nucl. Phys. A709(2002)419 Disfavor models with enhancement relative to binary collision scaling. Cannot discriminate between models that lead to suppression.

  22. J/y Signal in RUN4 Au-Au Collisions RUN4 is a dedicated Au-Au run for J/y: PHENIX recorded ~240mb-1 Au-Au collisions. We see signals from a small portion of AuAu (data less than 10%). J/y->mm J/y->ee

  23. Ncoll scaling has been observed for non-photonic single electron production in p-p, d-Au and Au-Au collisions. • Distinguish different scenarios of charm quark energy loss in medium require more statistics. Much more clear answer expected in RUN4 data. • Weak shadowing and absorption has been observed in both central and forward region J/y production. A modest baseline for Au-Au J/y has been established. • RUN2 Au-Au data disfavor J/y enhancement • RUN4 has accumulated 50 times more data and already see clear J/y signal. • PHENIX has proposed for future: • light nuclear collision at snn=200GeV to study the system size dependence of charm production. • Au+Au at snn=62.4GeV to study the energy dependence of charm production. • long snn=200GeVwith the new Silicon Vertex Detector which will open a much broader new territory for PHENIX charm physics. • (Details see Gerd’s talk on Future of Charm Measurement in PHENIX this afternoon) Summary and Future Perspective

  24. BACK-UP SLIDE

  25. Single Electron pp, d+Au, Au+Au

  26. XF = Xd - XAu E866: PRL 84, 3256 (2000)NA3: ZP C20, 101 (1983) Comparision with lower s • Energy loss expected to be weaker with increasing s (B. Kopeliovich et al., Nuclear Physics A696(2001)669-714) • Energy loss dominant at SPS • Shadowing start to be significant in at E866 energy • Energy loss negligible at RHIC X2 (in gold)

  27. J/Psi pT distributions J/  +- J/  +-

  28. BBC South BBC North Spectator nucleons Au d d and Au participant nucleons Centrality analysis Au breaks up in our south beam counter • Define 4 centrality classes • Relate centrality to <Ncoll> through Glauber computation • <Ncoll> = 8.4 ± 0.7 <Ncoll> = 3.2 ± 0.3 Counts Peripheral <Ncoll> = 15.0 ± 1.0 Central MB South BBC Charge

  29. Comparison With PYTHIA PHENIX PRELIMINARY PYTHIA charm + bottom under predict the tail by a factor of ~2-3 PHENIX PRELIMINARY PYTHIA charm alone under predicts the data by a factor of 2-5 at moderated pt

  30. +332 -281 cc=709b±85(stat) (sys) PYTHIA comparison with PHENIX Non-Photonic Single Electron Spectra pp s = 200 GeV PHENIX PRELIMINARY PYTHIA tuned to low energy data1 Data is excess of PYTHIA charm + bottom above pt=1.5 GeV/c 1Phys. Rev. Lett. 88, 192303 (2002)

  31. J/y Measurement in Au-Au Collisions at snn=200GeV Incl. systematic errors 90% C.L. One standard deviation Binary scaling Most probable value Expectation with absorption (4.4 and 7.1 mb) NA50 points normalized to pp point

  32. Short history of RHIC [1] nucl-ex/0305030 [2] hep-ex/0307019

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